My hugely talented colleague Nat Melia passed his viva this week (whoop whoop), so as has become the tradition in Reading Met now he got a thesis themed cake. As he looks at the opening of shipping routes through Artic sea ice* I of course couldn’t pass up the opportunity to bake this one:
*Note the accurately diamond shaped sea ice floe rheology ( or ‘the shape the ice goes when there’s lots of it in bits’). My supervisor was the internal examiner so this was super important.
Headlines today have picked up on a study suggesting that a third of Antarctica’s emperor penguins could be wiped out by 2100.
What’s the problem? A predicted loss of sea ice means a loss of krill, the main food source for emperor penguins. Young krill need sea ice to survive as they eat algae that lives in it.
Tasty tasty krill (image National Geographic).
I thought sea ice was increasing in Antarctica? That may well be the case for now, and the study does suggest that penguin numbers may actually increase for a while, but eventually a decline in sea ice will cause a fall in penguin numbers much steeper than this increase. Can anything be done? The study’s authors suggest that putting in marine protection zones to prevent fishing in areas where penguins need to hunt for food may help, but they don’t expect that penguins will have much ability to adapt to changing conditions, unlike these clever climbing penguins.
Global number of breeding pairs of emperor penguins from 2009 to 2100. After a short spell of increase the population plummets. (Jenouvrier et al. 2014, Nature Climate Change)
You can read the full study here: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2280.html
Even though I’ve mostly stuck to Antarctica news so far this bit is important for two reasons. One it’s about melt ponds, which is what I look at but on the other side of the world, and two it’s the group that I’m part of at Reading, go CPOM!
Melt ponds on Arctic sea ice, copyright NASA Goddard Space Flight Center
The CPOM group at Reading have just released a prediction for the 2014 Arctic sea ice minimum. They did this by using the fact that there is a correlation between the fraction of sea ice covered by melt ponds (pools of melted ice) in spring and the minimum amount of ice that will then be present at the end of the summer.
The reason for this is to do with the ponds being darker than the surrounding ice, as you can see in the image above. This means that they absorb more energy from the sun, which can lead to warming and further melting.
What does this mean?
These short term predictions are mostly important for predicting shipping routes but the more we know about modelling processes such as the formation of these ponds the better models will be for predicting future extents- one of the greatest uncertainties in predicting future global temperature changes is sea ice level fluctuations.
The prediction has been entered into the Arctic Research Consortium of the United States (ARCUS) Sea Ice Prediction Network– an annual comparison between different scientists’ predictions, but we’ll have to wait until September to see if Reading’s efforts will do well in the rankings!
An infographic produced by University of Reading to go with today’s news.
Until recently it was thought that all emperor penguins bread on fast ice, that’s sea ice attached to the land; much easier to navigate than the cliffs of ice shelves (image Photo Volcania).
It has been well publicised recently that despite sea ice in the Arctic decreasing, sea ice in the Antarctic has been on the increase. Emperor penguins breed on sea ice, so surely this would be a good thing for the penguins?
Unfortunately, this isn’t the case- even though there is more ice forming it’s forming too late for the penguins’ breeding season. The climate of Antarctica is changing, it has warmed more than 5 times the global average over the last century. It is thought that one of the colonies discovered moved as a result of the late arrival of the sea ice, potentially due to a changing climate.
Penguin colonies can actually be spotted in satellite images such as the one below and it was a combination of this and aerial views from planes that alerted scientist to the fact that these colonies that have moved onto ice shelves.
A satellite image of an emperor penguin colony on an ice shelf (Image BAS/Digital Global). Guano is a term for penguin excrement.
It’s not known quite how the penguins manage to climb up cliffs onto the ice shelves as the colonies haven’t been studied up close but it is thought they might be able to shuffle up between ridges formed by draining water on the ice shelves.
Although it is bad news that the penguins are having to do this it’s a nice positive in their chances of future survival. Polar regions warm faster than other areas so this may not be the end of unusual penguin behaviour if the planet continues to warm.
An emperor penguin huddle. The males are left to look after the eggs while the females go off and hunt, they huddle together to try and survive the freezing conditions such as during the blizzard shown here (image Australian Antarctic Division).
The original research article (Fretwell et al.) is http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0085285
Radar measurements have shown that Antarctica is losing ice at twice the rate previously estimated- it is contributing to 0.45mm of sea level rise per year.
This work was carried out by the Centre for Polar Observation and Modelling (CPOM) at Leeds University- CPOM are the group I’m part of but I’m in the Reading branch so this is extra exciting.
Ice loss from Antarctica- look towards the West, the area around the Amundsen Sea was in the news last week. Image ESA/CPOM/M.McMillan/Leeds Uni
How much is being lost?
0.45mm of sea level rise might not sound like a lot but in terms of the amount of ice involved that’s 159 billion tonnes of ice disappearing each year- to use a media favorite comparison I make that over 6 million Olympic sized swimming pools of ice.
Isn’t Antarctica supposed to be gaining ice?
Sea ice around Antarctica has been increasing recently (this could be for several reasons including changes in ocean circulation and weather) but this is only sea ice- frozen sea water, floating on the sea. The ice loss in this study is ice coming from off of the land and going into the ocean.
Extra bit of cool science
The reason this radar information is so much better than anything we’ve had previously is because the satellite involved, Cryosat can penetrate cloud. Previous satellites couldn’t do this so estimates had to be made wherever there was cloud suing information from cloud free areas. We now have 96% satellite coverage of Antarctica which makes monitoring future changes much easier.